SHOW OF WEEK Apr. 21

VIETNAM PROGRAMMING--Television revisits the Vietnam War this week, 10 years after the fall of Saigon.

Reporters and camera crews have been flocking to Saigon, now known as Ho Chi Minh City, for the last month to assess the impact of the war there and to chronicle what life in Vietnam is like now. This material will be interwoven with similar reports from the home front, gauging what effect the war's loss has had on the United States and interviewing veterans and former government officials.

Among those making the trip to Vietnam were Jess Marlow and Walter Cronkite. Marlow, anchorman at KCBS-TV Channel 2, will begin a series of reports for the local station on Sunday's 6 p.m. newscast. The series, "Vietnam: Ten Years After," will continue in segments of about five minutes each for the next two weeks, all on the 6 p.m. newscasts.

Cronkite went to gather information for "Honor, Duty and a War Called Vietnam," a "CBS Reports" documentary that will air Thursday at 10 p.m. (Channels 2 and 8). He was accompanied by Rep. John S. McCain III (R-Ariz.), a former Navy pilot who was shot down over North Vietnam and spent 5 1/2 years in a prison camp there.

Another documentary retrospective will follow two days later on NBC. "Vietnam: The Unwinnable War," anchored by Tom Brokaw, will air Saturday at 10 p.m. (Channels 4, 36 and 39).

Ted Koppel, who covered the Vietnam War for ABC, also has gone back to Southeast Asia and will be filing reports for "World News Tonight" on Wednesday, Thursday and Friday. In addition, he will be anchoring "Nightline" as it airs live from Thailand on Thursday and Friday at 11:30 p.m. (Channels 7, 3, 10 and 42).

The 10-years-later look at the Vietnam War will continue through next week too. Bryant Gumbel will broadcast live from Ho Chi Minh City for the "Today" show on NBC, Koppel will be there on Monday night for a special hourlong edition of "Nightline," and Steve Bell will be reporting for ABC's "Good Morning America." There also will be daily reports by John Hart and Garrick Utley on the "NBC Nightly News," which then will be reworked into an hourlong special May 5.